Operation analysis of a phase‐shifted full‐bridge converter during the dead‐time interval

Abstract

During the dead-time interval for a phase-shifted full-bridge (PSFB) converter, switches can achieve zero-voltage switching (ZVS) operation by using the energy stored in the transformer leakage inductance to discharge or charge the output capacitance of the switches. The value of dead-time has a great effect on ZVS range so it is a key parameter that needs to be optimised during designing the converter. This study develops theoretical analysis to estimate the dead-time as a function of load current for PSFB converter. The equivalent circuits of PSFB converter during the deadtime interval with considering magnetising inductance are mainly analysed in this study. Compared with previous analyses, the influences of dead-time on ZVS range and efficiency are discussed in detail. The analysis results show that the magnetising inductance of transformer can ensure ZVS over a wide range of load conditions, especially under discontinued current mode operation, without a penalty on the heavy-load efficiency. By adjusting the dead-time dynamically, both conduction and switching losses can be reduced. A 1 kW prototype is implemented and experimental results are consistent with the theoretical analysis.

Simple soft‐switched phase‐shifted FB converter for reduced voltage stress and negligible duty cycle loss

“…In the worst case, the voltage across the incoming diodes has to go to zero from its full value, i.e. V 0 and the time taken for that is governed by the frequency of oscillation as given in (18) which comes on the order of few nanoseconds which is negligible (almost zero) compared with the half switching period which is few microseconds.…”

“…The other methods of achieving ZVZCS for PSFB are described in [15][16][17]. A detailed analysis of the PSFB converter during the dead time of the switches from the same leg and its effect on achieving the soft switching and efficiency were presented in [18]. Some new variants of the PSFB were proposed in [19][20][21].…”

Hybrid control scheme for mitigating the inherent DC‐current in the transformer in buck‐boost full‐bridge converter for an all‐electric motor drive system

“…For the front-end converter of the 270 V/2 kW PMSM motor drive system, isolated full-bridge topologies are commonly used [1][2][3][4][5][6][7][8][9]. A full-bridge resonant transition converter (FB-RTC) retains the features of a hard-switched PWM converter with the phase modulation scheme.…”

“…A full-bridge resonant transition converter (FB-RTC) retains the features of a hard-switched PWM converter with the phase modulation scheme. Different techniques are adapted to achieve a wide zero voltage switching (ZVS) range like dead band control [9], asymmetrical duty control [8], and modified full-bridge topology [10][11][12]. Various full-bridge topologies [8,10,13] are presented to reduce circulating currents in the converter but involve more components.…”

A New Control Method for a Bi-Directional Phase-Shift-Controlled DC-DC Converter with an Extended Load Range

“…For the sake of minimizing the size of the resonant inductor used to store sufficient energy for the lagging leg of the inverter bridge to achieve ZVS under a light load condition, many different improvement methods have been proposed, for example, a combined phase-shift control algorithm and frequency modulation was proposed to achieve ZVS over the full load range in [16]; new control methods [17][18][19][20] were used for the converters under a light load condition to improve efficiency; a converter containing two paralleled half-bridge inverters and an auxiliary inductor on the primary side is proposed [21], which allows the stored energy for ZVS operation to change adaptively with duty-cycle and thus reduces the output filter inductance; phase-shift control with an L-C-L filter could also be utilized for ZVS to improve the performance [22]; DC link voltage was adjusted dynamically by power factor correction (PFC) in order to relieve the stress on semiconductor switches and improve the converter efficiency [23]; a two-stage isolated bi-directional DC-DC converter was investigated [24] which could enlarge the ZVS region by interleaving the converter with supercapacitors; dead-time for the lagging leg of the inverter bridge was adjusted predictively to assist the switches to perform ZVS at light load [25]; two additional switches were connected in parallel with the lagging leg of the inverter bridge to reduce switching loss under light load [26,27]; a novel ZCS-ZVS power factor correction PFC converter was proposed [28] with an efficiency of higher than 97%; two additional low-current diodes were added to the center-tap of a transformer secondary to improve ZVS at light load [29]; some other researchers proposed different control methods [30,31] and accomplished ZCS for the lagging leg, while retaining ZVS for the leading leg [31]. Improved ZVS techniques for the active switches of the forward converter are also adopted [32] in order to reduce switching and conducting losses to deal with PV power and wind energy.…”